Field
Embodiments described herein relate generally to a stepper motor driver circuit.
Background Art
Stepper motors are characterized by the ease of open-loop control and high holding torque, and a lot of stepper motors are used in a wide variety of applications.
However, the stepper motors have problems of noise during driving and driving efficiency.
Micro-step driving is an existing technique to reduce the vibration of the stepper motor.
The micro-step driving is a technique of smoothly driving the stepper motor by supplying a stepwise driving current that varies in smaller steps to the stepper motor. In particular, a driving current having a pseudo-sinusoidal waveform is close to a sinusoidal waveform, which is ideal for driving of the stepper motor.
The timing of transition between current steps is controlled in synchronization with a reference clock signal. When the stepper motor is driving at a constant number of revolutions, the frequency of the reference clock signal needs to be increased as the steps of the micro-step driving becomes smaller.
This leads to an excessive load on a mechanism control unit (MCU) that outputs the reference clock signal, and there is a limit to the vibration isolation based on the micro-step driving.